In an imaging apparatus including a photodiode array formed in a compound semiconductor, read-out electrodes of a silicon IC for signal read-out (ROIC: Read Out IC) face electrodes of those photodiodes, and conduction is made with bumps provided between the two types of electrodes. In an infrared range of a wavelength longer than that of a visible range, the photodiodes are formed of the compound semiconductor. Thus, it is sometimes called hybrid configuration of the compound semiconductor and the silicon (IC).
Crystals of that compound semiconductor are weak against mechanical force. Thus, soft indium (In) having a low melting point is often used for those bumps. Due to such characteristics thereof, the indium bumps are liable to deformation and become non-uniform when these are mounted on the electrodes of the photodiodes or the read-out electrodes of the ROIC. Several tens of thousands to several hundreds of thousands of bumps are provided for each imaging apparatus, and it is difficult to prevent the bumps from being greatly deformed. For example, Patent Literature 1 and Patent Literature 2 have proposed measures against it.